Here you can see how well creating bookdown documentation with beautiful themes work.
Installation of this library uses composer. For composer documentation, please refer to getcomposer.org.
run php composer.phar install
export CSS_BOOTSWATCH=superhero
run export CSS_BOOTSWATCH=superhero && export CSS_PRISM=dark && php vendor/bin/bookdown path/to/book/bookdown.json
Now you will find the bookdown documentation under the html directory.
Information about to change themes or generate the book via a docker container you can find at bookdown-bootswatch-templates.